There is no perfect time to start.
So start now.
You may have some issues getting into correct positions however, working with a SS coach will avoid that and may other beginner issues.
The best powerlifters weigh much more than you, so get strong first, then worry about your size (google Jezza Uepa) You may find that the process of losing the fat will be easier if you are carrying more muscle.
Jordan maintains the Nutrition forum and his posts have plenty of good information....find his article, To Be a Beast for some basic nutrition guidelines.
You may also need to see a doctor before embarking on any strenuous exercise, but unless there are some existing issues, you should not have any issues following novice progression.